How do I handle my mother-in-law to be's rude question?

My fiance's mother just emailed to remind me that she has special dietary needs that must be met by the wedding menu (it's a weekend wedding). Why this is rude: we share the same dietary problem- OF COURSE I will make sure there is food for us to eat. She even asked if she needed to bring a cooler! Also- the wedding is still 8 moths away. How do I handle this? I feel like sending back something equally rude but I won't hurt my fiance that way.